Wind power plant

ABSTRACT

The invention relates to a wind turbine ( 100 ) with a tower ( 10 ). The present invention is based on the task of advancing a wind turbine ( 100 ) in such a way that high degrees of efficiency in the use of input wind energy are maintained along with reduced production costs for wind turbines ( 100 ) and simple design features in the construction of the tower ( 10 ). The task is solved by said tower ( 10 ) being a timber-made hollow body, that said tower ( 10 ) consists of modules in the form of segments ( 16 ), which are arranged on top of each other, and that said segments ( 16 ) consist of timber panels ( 17, 18, 19, 20 ).

TECHNICAL FIELD

The invention relates to a wind turbine with a tower.

PRIOR ART

Wind turbines of the kind mentioned herein above are known and familiarto those skilled in the art.

Atop the wind turbine tower, the machine nacelle is arranged. At the endof the nacelle, a rotor with a horizontally extending pivotal axis isarranged and connected to a generator. It is common practise to usethree blade rotors, as they guarantee for a relatively consistent run.Wind turbines of this kind are highly advanced in terms of theirefficiency in utilizing input wind energy. Nonetheless, existing windturbines show significant economic disadvantages. For example, the heavyweight of the rotor and its distance from the tower center which carriesthe pivot-mounted nacelle results in considerable torque at the towertop. This leads to increased load on the tower along with aconsequential increase in construction and manufacturing costs,resulting in high material costs for the tower.

The most common design for wind turbines is based on steel tubingconstructions, whereupon the tower load is transferred via a tube or asteel skeleton framing (grid tower) into the ground. In technical terms,such steel tubes are referred to as shell or membrane, and the

skeleton framing as linear member. This technical terminology is basedon static considerations.

Wind turbine towers vary in height. In general, it may be stated thatthe energy yield correlates with the height of the wind turbine tower,resulting in heights well above 100 m. Eventually, it can be noticedthat not least there is an economic correlation between the constructioncosts and the yield on energy production, whereby, according toexperience, construction costs will rise to disproportionately highlevels with increased height of the wind turbine. There have beenapproaches to construct timber skeleton framings (grid towers) on thegrounds that timber is available in sufficient quantities and atreasonable costs. Nonetheless, there are no timber grid towers existingfor wind turbines, in as much as the attempt to construct timberskeleton framings for wind turbines uncovered two grave problems. Thefirst one is that the geometry of the tower is predetermined in oneaspect: The dimension of the rotor and the physical proximity of themoving rotor blade is limiting the possible dimension of the tower atthe virtual contact point.

At this point, the tower construction requires smaller distances betweenthe trusses of the skeleton framing, whereby the diameter that can bechosen for the tower is limited. In expert terminology, this problem isalso being referred to as tip/tower or open air problem. The momentum ofthe load is transferred by large axial forces. In terms of dimensioning,this results in very large and unwieldy and rod cross section radiuses,which are practically not manageable.

Moreover, the skeleton tower of a wind turbine consists of severalhundred rods with two to three junctures each. Each of these juncturesmust be constructed in a way that it can absorb the working load,offering sustainable resistance to the weather conditions at the sametime. State of the art technologies allow the production of suchjunctures. Yet these fasteners are custom-made and require sumptuousproduction processes, whereas rod connection elements are considered inthe first instance.

A significant problem in the construction of timber wind turbine towersis certainly posed by the restricted choices in planning regarding theavailable geometric options in the rotor area. The external diameter ofthe tower cannot be easily enlarged. Moreover, as mentioned above thetotal diameter of the tower depends on the rotor specifications. Giventhat considerable loads result from the weight of the said rotor, theworking loads cannot be easily absorbed by the components of the gridtower.

DESCRIPTION OF THE INVENTION

Based on the disadvantages detailed herein above, and in considerationof the current state of the art in the area of wind turbines of the kindfirst above indicated, the present invention is based on the task ofadvancing a wind turbine of the kind first above indicated in such a waythat high degrees of efficiency in the

use of input wind energy are maintained along with reduced productioncosts for wind turbines and simple design features for towerconstruction.

This task is solved by a wind turbine with the characteristics indicatedin claim 1. Advantageous designs and further embodiment of the presentintervention are characterized in the subclaims.

According to the invention, the wind turbine tower is a timber-madehollow body.

The advantages of the invention are relative to the construction. Thecomponents allow for easy on-site mounting. For example, the componentscan consist of glued timber panels. The easy on-site mounting of thecomponents, as compared to state of the art constructions, results inlogistical advantages. Timber components can generally be produced nearthe wind turbine location. Moreover, the components are handy, wherebycomplicated heavy goods transport become avoidable. (It is common toproduce and transport state of the art wind turbine towers segment-wise.The segments are huge and require heavy means of transportation).

Another advantage lies in the closed construction of the timber towers.In comparison to shoring constructions, the closed construction of thetimber towers protects the necessary fasteners. Insofar,

the wind turbine according to the invention will be less exposed toweather conditions.

In addition, timber has a number of advantages over concrete and steel.Concrete and steel are expensive and scarce resources which are onlyavailable on the condition of high CO2 emissions. Further, the worldmarket has seen steel prices soaring in the recent past. On the otherhand, timber is readily available and comparably easily processed. Thecreation of value is not bound to a certain location but can beperformed by local companies. For state of the art steel towers,however, manufacturing requires highest quality welding which can beperformed only by specialist firms.

To respond to static requirements, one advantageous embodiment of theinvention includes a tower diameter that expands as it approaches theground. The segments can be cone-shaped, that is, that the diameter ofthe towers inclines with increasing proximity to the ground. Thecone-shaped segments can be of 20 to 30 m length and be equipped withbeads on both ends to allow for immediate on-site mounting. Theincreasing diameter towards the ground produces more resilient towers.The cone shape reduces material input.

Preferably, the segments of the tower have polygon-shaped diameters. Inparticular, the polygons can be quadrilateral or pentagonal. Thesegments can be constructed with assembled and glued timber panels.

Other connection types to interconnect the timber panels are alsoconceivable.

One practicable variant of the invention provides for glued modulesand/or segments. Gluing is a cost-effective and simple connection typefor timber parts. Bolting of the modules and/or segments is alsoconceivable. An alternative way of connecting the segments are beads onboth ends that allow for on-site mounting at the wind turbine location.

A different option for connecting segments and/or modules is theconnection through plane timber panels which are arranged in between themodules and/or segments, whereas the modules and/or segments can beglued to said panels.

The tower can feature different types of timber. Selection criteria canbe hardness and weight of the timbers. Light timber types are spruce,fir, maple, birch, alder, pine, linden tree, walnut, or cherry tree,whereby the single segments may consist of different types of timber.The same applies to the timber panels for the production of the segmentsif derived timber products are used.

Another advantageous design of the invention provides for the towerbeing constructed in lightweight mode of construction. The tower isstill considered to be the “heaviest part of a wind turbine”, which hasan impact on transport costs.

Preferably, the tower is closed at the top and/or the bottom. This may,for example, be achieved by arranging timber panels onto the topmostsegment and/or under the lowermost segment of the tower structure andconnecting them to these.

Eventually, the invention provides for the application of a toweraccording to claims 1 to 14 in connection with a wind turbine.

Exemplary designs of the invention are illustrated in the followingfigures.

SHORT DESCRIPTION OF THE FIGURES

Showing in a schematic way:

FIGS. 1 a and 1 b a wind turbine according to the invention in frontview and side view;

FIG. 2 a tower of said wind turbine according to the invention;

FIG. 3 a segments of said tower, which are arranged on top of each otherand

FIG. 3 b in exploded view: the construction of one of the said segmentsof said timber tower according to the invention.

DETAILED EMBODIMENT OF THE INVENTION

In FIGS. 1 a and b, a wind turbine according to the invention in frontview and side view is illustrated and provided with the referencenumeral 100.

The wind turbine 100 consists of a tower 10, with a machine nacelle 13which is pivotable around a vertical shaft arranged at the free end ofthe tower, a rotor shaft 12 and a rotor 11 consisting of more than onerotor blades and connected to the rotor shaft 12.

The height of the tower 10 results from the intended hub height of therotor 11, which again results from the intended diameter of the rotor 11depending on the designated wind turbine performance. Accordingly, thetower 10 can be of up to 100 m height. The tower 10 is a timber-madehollow body that is formed tapering with increasing height from the base15 upwards. As can be obtained form FIG. 1 b, the rotor hub is arrangedin such a distance from the tower top 14 that a space between rotorblades 11 and the exterior of the tower 10 remains, so that any contactbetween the rotating rotor blades 11 and tower 10 is impossible.

The embodiment of the tower 10 as illustrated in FIG. 2 consists of atotal of 8 segments 16 arranged on top of each other that can, forexample, be glued to each other. The segments 16 arranged on top of eachother can be of the same length or have differing dimensions asillustrated in the presented embodiment. The presented embodiment showssegments 16 with increasing length towards the top. It is conceivable,however, that the segments 16 are of equal length.

The geometry of the external periphery of the segments 16 can vary. Itis conceivable that the external periphery of the segments 16 isdesigned in circular shape. The presented embodiment includes segmentsof a preferably quadrilateral polygon diameter. In addition, it can beobtained from FIG. 2 that the single segments 16 are arranged with theirrespectively larger diameter underside the subjacent segment 16, e. g.onto the respectively smaller diameter of the respective segment 16thereunder.

The tower 10 tapers off in a segment 16 which is referred to as towerhead in the terminology used herein. At the tower head, the nacelle 13,which is not part of the illustration herein, is situated and can be oflateral and longitudinal dimensions of 5 m×3 m or of 6 m×4 m. The timberconstruction of the tower allows for several tons of total weight of thenacelle 13, the included generator and gearbox and the rotor 11.Dimensions and weights differ for different embodiments. Insofar theindications herein only serve as an example and it is understood thatthe invention is not limited by them. The tower 10 can be closed bymeans of timber panels at the top and the bottom.

As can be obtained from FIG. 3 a, the modules are arranged in the shapeof segments 16 on top of each other. The single segments 16 consist oftimber panels 17, 18, 19 20, which are connected to each other. Theconnection type can be glue. The cross sections of the segments 16

increase towards the bottom of the tower, whereby the segments 16 canhave different shapes. The embodiment presented herein provides forsegments 16 in a polygon shape, whereby the timber panels 17, 18, 19, 20are of trapezoidal shape. All timber panels 17, 18, 19, 20 of a segment16 feature identical dimensions, whereby the trapezoidal planes shrinktowards the tower top within a segment 16. Thus it is ensured that thetower tapers towards the top, whereby the single segments 16 aredirectly arranged on top of each other, that is, without an additionalpart interposed. It is nevertheless conceivable that timber panels areinterposed and glued in between the segments 16 to interconnect thesegments 16. The segments 16 are arranged precisely fitting on top ofeach other, that is, that the smallest dimension of one segment 16 iscongruent with the largest dimension of the following segment 16.

FIG. 3 b demonstrates the easy mounting of a segment 16 from timberpanels 17, 18, 19, 20. The timber panels 17, 18, 19, 20 can be producedin a previous process directly at a wind turbine location. By gluing thesingle timber panels 17, 18, 19, 20, which are of trapezoidal shape inthe presented embodiment, one segment 16 of the timber tower is created.

REFERENCE LIST

100 Wind turbine

10 Tower

11 Rotor

12 Rotor shaft

13 Nacelle

14 Tower top

15 Base area

16 Segments

17 Timber panel

18 Timber panel

19 Timber panel

20 Timber panel

1-14. (canceled)
 15. A Wind Turbine Tower, comprising a hollow body ofstacked segmented modules constructed from timber panels.
 16. A WindTurbine Tower according to claim 1, wherein the cross section of themodules decreases from bottom to top of the tower.
 17. A Wind TurbineTower according to claim 2, wherein the modules are cone-shaped.
 18. AWind Turbine Tower according to claim 1, wherein the modules are of apolygon cross section, including quadrilateral and pentagonal crosssections.
 19. A Wind Turbine Tower according to claim 1 wherein themodules are interconnected by at least one of adhesive or boltingtogether.
 20. A Wind Turbine Tower according to claim 1 wherein thepanels are connected by at least one means of connection includingadhesive.
 21. A Wind Turbine Tower according to claim 1, furthercomprising timber panels disposed between the modules.
 22. A WindTurbine Tower according to claim 1, comprising at least two types oftimber.
 23. A Wind Turbine Tower according to claim 1 wherein the panelsare of a trapezoidal shape.
 24. A Wind Turbine Tower according to claim1, wherein the tower is closed at at least one of the top or bottom ofthe tower.
 25. A Wind Turbine Tower according to claim 1, wherein thetimber panels are constructed of a derived timber product.
 26. A WindTurbine Tower according to claim 1, wherein the timber panels areconstructed from at least two types of timber.